I am using the default Amazon Linux AMI in an EC2 instance - Amazon Linux AMI release 2010.11.1. I can see that it's a Redhat based system, but after trying many tools (/etc/issues, uname -a, lsb_release), I cannot tell which version of RHEL or CentOS is it based on. I need to get some packages that are not available in Amazon's package repos. I have list of custom yum repos that I can use, but since I don't know which RHEL version is the Amazon AMI based on, I cannot choose from different versions of repos.
How can I find whether it's running RHEL 4/5/6 (or their CentOS counterparts)?